Electronic Stability Control (ESC) is the generic term for systems designed to improve a vehicle's handling, particularly at the limits where the driver might lose control of the vehicle.

Robert Bosch GmbH were the first to deploy an ESC system, called Elektronisches Stabilitätsprogramm (ESP®) that was used first by Mercedes-Benz and BMW in 1995. It was then introduced to the mass market by Continental Automotive Systems under the broader name of Electronic Stability Control, which is now the more common term recognized by the Society of Automotive Engineers, although individual motor manufactures use a range of different marketing names (see below).

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Operation

ESC compares the driver's intended direction in steering and braking inputs, to the vehicle's response, via lateral acceleration, rotation (yaw) and individual wheel speeds. ESC then brakes individual front or rear wheels and/or reduces excess engine power as needed to help correct understeer (plowing) or oversteer (fishtailing). ESC also integrates all-speed traction control, which senses drive-wheel slip under acceleration and individually brakes the slipping wheel or wheels, and/or reduces excess engine power, until control is regained. ESC cannot override a car's physical limits. If a driver pushes the possibilities of the car's chassis and ESC too far, ESC cannot prevent a crash. It is a tool to help the driver maintain control.

ESC combines anti-lock brakes, traction control and yaw control (yaw is spin around a vertical axis). To grasp how it works, think of steering a canoe. If you want the canoe to turn or rotate to the right, you plant the paddle in the water on the right to provide a braking moment on the right side. The canoe pivots or rotates to the right. ESC fundamentally does the same to assist the driver.

Effectiveness

Numerous international studies have confirmed the effectiveness of ESC in helping the driver maintain control of the car, help save lives and reduce the severity of crashes. In the fall of 2004 in the U.S., the National Highway and Traffic Safety Administration confirmed the international studies, releasing results of a field study in the U.S. of ESC effectiveness. NHTSA concluded that ESC reduces crashes by 35%. The prestigious Insurance Institute for Highway Safety later issued their own study that concluded the widespread application of ESC could save 7,000 lives a year. That makes ESC the greatest safety equipment development since seat belts, according to some experts. However, some people contend (backed up by the theory of risk compensation) that the perception of safety conferred by the ESC will encourage more dangerous driving, as seems to be the case with seat belts.

Criticism

Some driving enthusiasts, most publicly motoring journalists from enthusiast magazines, object to some of the implementations of ESC. They contend that by making it impossible to explore the dynamic behaviour of their cars, overzealous ESC systems spoil much of the fun of driving. Consequently, some manufacturers allow drivers to disable ESC systems, or provide a setting that allows greater levels of under or oversteer before the ESC intervenes. Enthusiasts have also begun to modify ESC systems to suit their preferred driving styles [1].

Future

Electronic Stability Control forms the foundation for new advances on vehicle equipment that will save additional lives and give the driver still more control over the vehicle. The computing power of ESC facilitates the networking of active and passive safety systems on the car, creating the opportunity to address still more causes of crashes.

In the US, the NHTSA is currently evaluating whether ESC should be mandatory on all passenger vehicles, due to the effectiveness noted above.